The invention relates to an improved aqueous corrosion inhibitor for metal surfaces which, as a result of the use of certain substances, has a considerable corrosion-inhibiting effect and, at the same time, provides special advantages from the point of view of application techniques.
Treatment with aqueous solutions containing corrosion-inhibiting additives is usually carried out in order to prevent unwanted corrosion phenomena. More or less strongly alkaline solutions of this kind are used for temporary protection against corrosion, especially during production of metallic workpieces, during or after cleaning treatments, during machining, or during temporary storage prior to further processing stages. Known corrosion-inhibiting additives are, for example: alkali nitrites, alkali chromates or other organic compounds such as alkanolamines, more particularly triethanolamine, or alkali- or alkanolamine-soaps of fatty acids of intermediate chain length. Nitrites and chromates have the disadvantage that special measures must be taken to process the solutions before releasing them into the waste water. The corrosion protection achieved with alkanolamines or fatty-acid salts is frequently inadequate and more nitrite is therefore added to the solutions, but this once more leads to the operational disadvantage mentioned above.
There exists, therefore, a requirement for a corrosion inhibitor which has a considerable corrosion-inhibiting effect, which has many applications, and which is innocuous in waste water.